*2.5. Effect of Coatings on CO<sup>2</sup> Production*

subsequently, low CO2 production [38].

CO2 (%)

0

5

10

15 CON

Ch SA+C ChCSA

Aab Ab

*2.5. Effect of Coatings on CO2 Production*  The thin film layer formed by coatings on the food surface controls gas permeability, and provides a delicate balance between inhibiting over-ripening and preventing senescence. In addition, it regulates normal gas exchange to avoid the buildup of CO2, which promotes anaerobic conditions that lead to off flavors [37]. High rate of respiration is one The thin film layer formed by coatings on the food surface controls gas permeability, and provides a delicate balance between inhibiting over-ripening and preventing senescence. In addition, it regulates normal gas exchange to avoid the buildup of CO2, which promotes anaerobic conditions that lead to off flavors [37]. High rate of respiration is one of the problems for fresh-cut products [11]. The composition of CO<sup>2</sup> in the headspace gas

of the problems for fresh-cut products [11]. The composition of CO2 in the headspace gas

concentration slowly increased in all samples until the end of storage. Notably, a sharp increase in CO2 production was observed in uncoated fresh-cuts compared to the coated samples. Gel coatings (SA + C and ChCSA) showed better effectiveness in retarding CO2 production. High CO2 production in fruits corresponds to high oxygen consumption. Thus, the low oxygen permeability of coated samples resulted in tissue respiration, and

**Figure 6.** The effect of layer-by-layer and single-layer coatings on the percentage of carbon dioxide gas emission on fresh-cut purple sweet potatoes. Vertical bars represent means and standard deviation. Bars with different alphabets within the same storage day (lower case) or same treatment group at different storage days (upper case) are significantly different (Tukey's HSD Test, *p ≤* 0.05).

Storage Time (days) 4 8 12 16

Bb Ab

Aa Aa

Cc

Bb

Ba Ba

Aab Aa Aa Aa Aa Aa

was used to explain the rate of respiration in packaged samples (Figure 6). There were no noticeable differences in CO<sup>2</sup> production during the first 8 days of storage. Thereafter, CO<sup>2</sup> concentration slowly increased in all samples until the end of storage. Notably, a sharp increase in CO<sup>2</sup> production was observed in uncoated fresh-cuts compared to the coated samples. Gel coatings (SA + C and ChCSA) showed better effectiveness in retarding CO<sup>2</sup> production. High CO<sup>2</sup> production in fruits corresponds to high oxygen consumption. Thus, the low oxygen permeability of coated samples resulted in tissue respiration, and subsequently, low CO<sup>2</sup> production [38]. was used to explain the rate of respiration in packaged samples (Figure 6). There were no noticeable differences in CO2 production during the first 8 days of storage. Thereafter, CO2 concentration slowly increased in all samples until the end of storage. Notably, a sharp increase in CO2 production was observed in uncoated fresh-cuts compared to the coated samples. Gel coatings (SA + C and ChCSA) showed better effectiveness in retarding CO2 production. High CO2 production in fruits corresponds to high oxygen consumption. Thus, the low oxygen permeability of coated samples resulted in tissue respiration, and subsequently, low CO2 production [38].

**Figure 5.** The effect of single-layer and gel coatings on the yeast and mold on fresh-cut purple sweet potatoes. Vertical bars represent means and standard deviation. Bars with different alphabets within the same storage day (lower case) or same treatment group at different storage days (upper case)

Ba Bb

Cb

BbAa

Ba BaAa

Db

Storage Time ( days) 0 4 8 12 16

BbAb Ba Aa

Bb

The thin film layer formed by coatings on the food surface controls gas permeability, and provides a delicate balance between inhibiting over-ripening and preventing senescence. In addition, it regulates normal gas exchange to avoid the buildup of CO2, which promotes anaerobic conditions that lead to off flavors [37]. High rate of respiration is one of the problems for fresh-cut products [11]. The composition of CO2 in the headspace gas

*Gels* **2022**, *8*, x FOR PEER REVIEW 6 of 14

are significantly different (Tukey's HSD Test, *p ≤* 0.05).

Ac

Bb

*2.5. Effect of Coatings on CO2 Production* 

Yeast and Mold count (log CFU/ml)

0

1

2

3

Ac

Aa

Aa

Ab

CON Ch SA+C ChCSA

4

5

**Figure 6.** The effect of layer-by-layer and single-layer coatings on the percentage of carbon dioxide gas emission on fresh-cut purple sweet potatoes. Vertical bars represent means and standard deviation. Bars with different alphabets within the same storage day (lower case) or same treatment group at different storage days (upper case) are significantly different (Tukey's HSD Test, *p ≤* 0.05). **Figure 6.** The effect of layer-by-layer and single-layer coatings on the percentage of carbon dioxide gas emission on fresh-cut purple sweet potatoes. Vertical bars represent means and standard deviation. Bars with different alphabets within the same storage day (lower case) or same treatment group at different storage days (upper case) are significantly different (Tukey's HSD Test, *p* ≤ 0.05).

By modifying the gas atmosphere around the fruit tissue, polysaccharide coatings with semipermeable properties on the surface of fruits impede the rate of respiration and ripening during storage, thus retaining the quality attributes of products [39]. Similar gaseous barrier effects of polysaccharide-based coatings on fresh-cut products have been reported [33,40].
